Claim CA131:

Charles Darwin became chronically ill shortly after returning from his
voyage on the Beagle, making him an invalid for much of his life. His
symptoms -- depression, vomiting, palpitations, etc. -- match no organic
illness and appear to be psychogenic (originating in his mind). The cause
of this illness could be anxiety that his theory was wrong or guilt from
rejecting God.

Response:

Many different diagnoses have been proposed for Darwin's illness,
generating much controversy (Smith et al. 1990; Alder et al. 1997;
Campbell and Matthews 2005). An organic cause for Darwin's illness is
entirely possible. Both Chagas' disease (Alder 1959; Pasnau 1990) and
systemic lactose intolerance (Campbell and Matthews 2005) explain most
or all of his symptoms. Some have taken his symptoms as evidence for
panic disorder with agoraphobia (Barloon and Noyes 1997), but the
symptoms can also be direct symptoms or other consequences of the above
organic illnesses. For example, a relatively secluded lifestyle and
occasional depression are normal reactions to a chronic illness. Other
symptoms, such as anxiety upon leaving home on the Beagle, may be
entirely normal. The timing of his symptoms does not fit all that well
with a psychosomatic cause but does fit well with systemic lactose
intolerance (Campbell and Matthews 2005).

Even if Darwin's illness was an anxiety disorder, such a disorder has
nothing to do with being psychotic. It is a genetic disease which
causes synapses in the fight-or-flight region of the brain sometimes to
fire more than they should. The disease is typically associated with
above-average intelligence.

The theory of evolution is based on evidence, not on the authority of
Darwin. Aspects of Darwin's life are of historical interest, but
they have no relevance to science.

Some people can achieve great things while suffering seemingly
debilitating conditions.

John Nash suffered schitzophrenia but won a Nobel prize in economics
for his application of game theory.

Stephen Hawking has done most of his work in physics after becoming
wheelchair-bound from ALS (Amyotrophic Lateral Sclerosis).

Florence Nightingale did much to reform the British public health
system while an invalid.

Darwin researched and wrote several major books on diverse subjects
(including orchids, barnacles, the expression of emotions,
insectivorous plants, and earthworms) while chronically ill.